In the technologies of renewable energy and energy recovery, dye-sensitized photovoltaic cells have a high potential. A photosensitizing dye on a working electrode of a dye-sensitized photovoltaic cell absorbs external optical energy, and electrons contained in the photosensitizing dye are thus excited and effectively injected into a conduction band of a semiconductor of the working electrode and are then conducted from the working electrode to a counter electrode through an external circuit so as to produce a photoelectric current. Therefore, the quality of the photosensitizing dye may affect the photoelectric conversion efficiency of the dye-sensitized photovoltaic cell.
The types of photosensitizing dye commonly used in the dye-sensitized photovoltaic cells include ruthenium complexes, porphyrin derivatives, and organic photosensitizing dyes. The ruthenium complexes have a relatively low molar absorption coefficient in a visible light region, metallic ruthenium is costly and rare, and ruthenium oxides are toxic. Therefore, the application of ruthenium complexes is limited. While porphyrin derivatives have high photoelectric conversion efficiency, the process for the synthesis of porphyrin derivatives is complicated and costly, so that porphyrin derivatives have not yet been commercially used as a photosensitizing dye in the manufacture of dye-sensitized photovoltaic cells.
The organic photosensitizing dyes are relatively simple in terms of chemical structure and synthesis process, and have the advantages of relatively low production cost and no heavy metal pollution as compared to ruthenium complexes and porphyrin derivatives. However, the photoelectric conversion efficiency of organic photosensitizing dyes is generally lower than those of ruthenium complexes and porphyrin derivatives. Therefore, it is an important trend in the field of dye-sensitized photovoltaic cells to develop an organic photosensitizing dye having enhanced photoelectric conversion efficiency.
An article entitled “Cost-Effective Anthryl Dyes for Dye-Sensitized Cells under One Sun and Dim Light” by Chin-Li Wang et al. in The Journal of Physical Chemistry C 2015, 119, 24282-24289 discloses an organic photosensitizing dye represented by Formula A:
wherein
A1 is selected from the group consisting of
and
A2 is selected from the group consisting of

Although the organic photosensitizing dye represented by Formula A may be applied in the dye-sensitized photovoltaic cell, the wavelength range of the light which may be absorbed by the organic photosensitizing dye represented by Formula A is relatively narrow such that the dye-sensitized photovoltaic cell containing the organic photosensitizing dye may not produce a satisfactorily high photoelectric current.
It is thus desirable in the art to develop an organic photosensitizing dye which may absorb visible light over a relatively wide wavelength range.